Electrical Drain

TopHat9000

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Thought I would run this by you all to see if there are some obvious troubleshooting things to try. I don't have time at the moment for major bike surgery.

The bike is running fine mechanically, but has a battery issue. I'll take it off the trickle charger in the morning and it starts right up using the electric start. I let the bike warm up for five minutes and ride to the store which is five minutes away. In the parking lot it won't start again using the electric start. There's a click and a low-volume whirring sound, but there is no starter engagement. It kick starts immediately on the first try. I notice on this ride that the blinkers and other lights start to fade away really fast and I need to resort to hand signals.

A newer AGM battery is installed, the negative and positive wire terminals are firmly secured to the battery posts, and the reg/rect swap-out has been done.

Where should I start looking?

Thanks everyone.
 
First thing that comes to mind is the warm-up time, which is below the rpm level of break-even charging point (about 2500 to 3000 rpm before charging goes positive) and possibly the rpm level of your ride there. Idling with the headlight on will immediately start the discharge of the battery, and if you ride at low rpm to the store afterward it might barely be breaking even which means the battery is at some level of discharge when you arrive at the store. You should pick up a cheap voltmeter you can connect to the battery and watch as you ride, and if on a longer ride the voltage doesn't get to at least 13.5 or higher then the charging output is low for whatever reason. Or, but less likely, the new AGM battery is defective.
 
TopHat9000 said:
A newer AGM battery is installed, the negative and positive wire terminals are firmly secured to the battery posts, and the reg/rect swap-out has been done.
Click to expand...
Do you have any anecdotal information about how the charging system worked before and after the installation of the new rec/reg?
  • Did you ever look at ac output from the coils or resistances in the different coil sections?
  • Did you install the new rec/reg system to solve a problem or prevent a future one?
  • Is the battery draining problem new? Or ongoing?
  • Battery age?
 
First easy test can be done in the garage. Hook your multimeter on DC 12V to the battery and (after warming up), take revs up to about 4500, you should see voltage climb up to the mid-13's.

If that's happening, likely failed battery.

If that's NOT happening:
Walk through the charging circuit wiring
1. Did you combine the yellow/white wires from the alternator prior to the rec/reg?
2. Did you add a separate voltage sensing wire to the 12V+ switched circuit (black) from the rec/reg?
3. Is the new rec/reg grounded directly to the battery, or via frame?

A parasitic drain is fairly rare on these bikes, but not impossible. I'd eliminate the stuff above first before the real gremlin hunt begins
 
stl360+450 said:
Do you have any anecdotal information about how the charging system worked before and after the installation of the new rec/reg?
  • Did you ever look at ac output from the coils or resistances in the different coil sections?
  • Did you install the new rec/reg system to solve a problem or prevent a future one?
  • Is the battery draining problem new? Or ongoing?
  • Battery age?
Click to expand...

I will check the battery at 4500 and check output levels in the next few days.
  • No
  • I installed thinking it would solve the electrical draining issue.
  • See answer above.
  • Unknown, but it looks pretty new. I bought the bike about 4 months ago, so the battery is at least that old.
 
EzPete said:
First easy test can be done in the garage. Hook your multimeter on DC 12V to the battery and (after warming up), take revs up to about 4500, you should see voltage climb up to the mid-13's.

If that's happening, likely failed battery.

If that's NOT happening:
Walk through the charging circuit wiring
1. Did you combine the yellow/white wires from the alternator prior to the rec/reg?
2. Did you add a separate voltage sensing wire to the 12V+ switched circuit (black) from the rec/reg?
3. Is the new rec/reg grounded directly to the battery, or via frame?

A parasitic drain is fairly rare on these bikes, but not impossible. I'd eliminate the stuff above first before the real gremlin hunt begins
Click to expand...

EzPete said:
First easy test can be done in the garage. Hook your multimeter on DC 12V to the battery and (after warming up), take revs up to about 4500, you should see voltage climb up to the mid-13's.

If that's happening, likely failed battery.

If that's NOT happening
Walk through the charging circuit wiring
1. Did you combine the yellow/white wires from the alternator prior to the rec/reg?
2. Did you add a separate voltage sensing wire to the 12V+ switched circuit (black) from the rec/reg?
3. Is the new rec/reg grounded directly to the battery, or via frame?

A parasitic drain is fairly rare on these bikes, but not impossible. I'd eliminate the stuff above first before the real gremlin hunt begins
Click to expand...
  1. I believe the yellow/white wire fix was done before my ownership, but I'll double check.
  2. I just hooked up the new unit like the internet told me to.
  3. Don't remember. I'll check next time.
 
I have spent much time before troubleshooting because of disbelief a brand new battery is a failure

Batteries can display adequate voltage with a multimeter but fall on their face under load

The easiest thing to do of course is to swap in a known good battery and see if that fixes it

My new rec/reg required a ground wire directly to the battery negative terminal, a fact not explained in the instructions or...anywhere
 
You can get a small digital Voltmeter on Amazon for about $5. Use layers of double-sided tape to conform to the handlebar between the clamps and run the wires into the headlight bucket where you can splice into a switched voltage source. Gives you an instant readout of your charging system while riding. You can also put your test meter on the 10 amp setting and put it in series with the disconnected positive or ground cable to see if you have a parasitic drain with the engine off.
 
Good advice, everyone. Thank you! Life is a little busy at the moment but I will try some of these solutions when I get the chance.

But while I am here, is there any consensus on a good battery brand/model to pick up?
 
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